The present invention relates generally to ramps used to facilitate moving objects, such as lawn mowers, from one elevation to another.
U.S. Pat. No. 2,607,937 to G. B. Stone teaches the use of a pulley positioned at the top of a frame for lifting the leading edge of a ramp into position. The runway of the ramp is raised and lowered via traverse shaft (44), which is rotatably journaled in brackets (46) affixed to cross bar (18). A handle (48) is attached at one end of the shaft (44) and a pair of cables is windable about the shaft (44). The Stone patent fails to teach the use of supporting structures, such as hooks, on both sides of an upright member and cooperating tabs on the side of the runway for manually positioning the runway relative to a base. The Stone patent further fails to teach the use of a channel along the base and tabs on the trailing edge of the runway for maintaining proper alignment of the runway while the runway is moved to different elevations relative to the base.
U.S. Pat. No. 2,449,829 to C. G. Agren teaches the use of a deck that may be raised and lowered by means of a hand-pump carried by a jack cylinder. Notably, the hand pump is positioned beneath the ramp and pushes the ramp into position. The Agren patent fails to disclose the use of a ramp positioning means, such as a winch, positioned above the runway. The Agren patent also fails to teach the use of supporting structures, such as hooks, on both sides of an upright member for manually raising and lowering the runway.
U.S. Pat. No. 4,155,468 to Royce teaches the use of a ramp for facilitating loading and unloading wheel chairs. The motor drive for the ramp assembly is positioned on the vehicle between the two pivotally mounted ramp members to further increase the available space within the vehicle. The Royce patent fails to disclose the use of supporting structures, such as hooks, on both sides of an upright member, for manually raising and lowering the runway. Royce further fails to teach the use of a channel along the base and tabs on the trailing edge of the runway, the tabs sized to fit within the channel, for maintaining proper alignment of the runway while the runway is adjusted to different elevations.
U.S. Pat. No. 5,333,340 to Moseley teaches the use of a mobile elevatable platform fitted with an impact absorbing bumper set at a height above the ground to meet the horizontal bumper on the rear of a truck.
What is needed, then, is a ramp that is easy to build and maintain, that is sturdy and suitable for loading and unloading heavy machinery, that is capable of both manual and electric operation, that utilizes supporting structures and cooperating tabs, or protrusions, for adjusting the elevation of the runway, and that utilizes a guide structure for guiding the rear of the runway when the runway is moved relative to the base.
It is an object of the present invention to provide a ramp that is relatively easy to build and maintain when compared to conventional ramps.
It is another object of the present invention to provide a ramp that is sturdy and suitable for loading and unloading heavy machinery.
It is still a further object of the invention to provide a ramp that may be operated both manually and automatically.
It is yet another object of the invention to provide a ramp that utilizes supporting structures and cooperating tabs, or protrusions, for adjusting the elevation of the runway relative to a base.
It is still another object of the present invention to provide a ramp that utilizes a guide structure for guiding the rear of the runway when the runway is moved relative to the base.
To overcome the disadvantages of the prior art and to achieve the objects and advantages mentioned above, a ramp is disclosed comprising a base having a first guide structure defined thereon. The first guide structure may take on any suitable structure; in the preferred embodiment, the first guide structure comprises at least one channel along at least a portion of the base.
An upright member is fixed to and extends upwardly from the base. The upright member has a plurality of supporting structures defined thereon at differing elevations above the base. In the preferred embodiment, the supporting structures comprise hooks.
A runway has a first end and a second end. The first end of the runway is movable between a plurality of positions relative to the base. A plurality of supported members is fixed to the first end of the runway and selectively engagable with one of the supporting structures to elevate the first end of the runway above the base. In the preferred embodiment, the supported members comprise a plurality of protrusions, each of which is adapted in size and shape to be received in the corresponding hook and to be operatively engaged therewith.
A second guide structure is fixed to the second end of the runway and is operatively engaged with the first guide structure of the base, so that the second end of the runway may move relative to the base when the elevation of the first end of the runway is adjusted. The second guide structure may take on any structure suitable to accomplish its intended purpose; in the preferred embodiment, the second guide structure comprises a plurality of protrusions, extending outwardly from the runway, wherein each protrusion is adapted in size and shape to be received in the channel of the base.
In another preferred embodiment, a movable ramp is disclosed comprising a base having a first end and a second end, and a frame having a top. The frame is fixed to the first end of the base and extends upwardly therefrom. A runway, having a leading edge and trailing edge, is movable between a plurality of positions relative to the base. The trailing edge of the runway is fixed to the second end of the base and rotatable about at least a portion thereof. A winch is fixed to the top of the frame and connected to the leading edge of the runway for moving the runway between a plurality of positions. The winch may be either electric or manual, depending on the needs of the operator.